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7.3 The Complement System β Test 1
Q1. The complement system is best described as:β A cascade of plasma proteins that enhances immune defence
Q2. The central, most abundant complement component, pivotal to all pathways, is:β C3
Q3. The three main biological functions of complement are:β Opsonisation, inflammation, and cell lysis (via the MAC)
Q4. C3b primarily functions as an:β Opsonin that tags microbes for phagocytosis
Q5. The anaphylatoxins C3a and C5a act to:β Promote inflammation, recruit phagocytes and trigger mast-cell degranulation
Q6. The membrane attack complex (MAC) consists of:β C5b, C6, C7, C8 and multiple C9 molecules
Q7. The MAC kills target cells by:β Forming pores that cause osmotic lysis
Q8. Most complement proteins are synthesised by the:β Liver
Q9. Complement components circulate normally as:β Inactive precursors (zymogens) that are activated in sequence
Q10. Complement receptor CR1 (CD35) on phagocytes and red cells functions to:β Bind C3b for phagocytosis and immune-complex clearance
Q11. Complement helps clear immune complexes by:β Coating them with C3b so red cells (via CR1) carry them to the liver/spleen
Q12. Host cells are protected from complement damage by regulatory proteins such as:β DAF (CD55), CD59 and factor H
Q13. The complement system is considered part of which arm of immunity?β Innate immunity (but it links to adaptive immunity)
Q14. C5a is particularly important as a:β Potent chemoattractant that recruits neutrophils
Q15. Binding of C3b to a microbe and subsequent phagocytosis is an example of:β Opsonisation
Q16. Complement enhances B-cell responses through the receptor:β CR2 (CD21), which lowers the B-cell activation threshold
Q17. The 'amplification' feature of the complement cascade means that:β Each activated enzyme cleaves many substrate molecules, magnifying the response
Q18. Complement deficiency generally results in:β Increased susceptibility to infection and/or immune-complex disease
Q19. The covalent binding of C3b to surfaces is possible because activated C3b exposes a reactive:β Thioester group
Q20. The complement system can best be described as:β A cascade of ~20+ serum proteins acting in sequence
Q21. The complement system participates in:β Both specific and non-specific defence
Q22. The central molecule of the complement system is:β C3
Q23. Cell lysis in the complement pathway is initiated by the:β Membrane attack complex (MAC)
Q24. The membrane attack complex (MAC) is composed of:β C5b, C6, C7, C8 and C9
Q25. The anaphylatoxins generated during complement activation are:β C3a and C5a
Q26. The most potent chemotactic complement fragment is:β C5a
Q27. Functions of the complement system include:β Cell lysis, opsonisation, and anaphylatoxin/chemotactic activity
Q28. Host cells are protected from the membrane attack complex by a surface glycoprotein called:β DAF (decay-accelerating factor)
Q29. DAF prevents membrane-attack-complex formation by:β Destabilising the C3 and C5 convertases
Q30. Complement component C3b primarily functions as:β An opsonin that tags microbes for phagocytosis
Q31. Most complement components are, by basic nature:β Enzymes (zymogens activated in sequence)
Q32. Which statement about the complement system is correct?β It can form the membrane attack complex and mediates opsonisation and chemotaxis
Q33. Which complement protein initiates assembly of the membrane attack complex?β C5b
Q34. Heat-inactivation of serum (56Β°C for 30 minutes) is performed to inactivate:β Complement
Q35. Match each complement component/fragment with its role and select the correct option.β A-ii, B-i, C-iv, D-iii